1. Field of the Invention
This invention relates to means for transferring light between an optical fibre housed within a fibre management unit and an external optical device, and in particular to a probe for tapping out light from optical fibres in a splice tray.
2. Related Art
An optical fibre splice tray usually houses many (typically 16) spliced optical fibres. In the typical case, therefore, it has 16 input fibres, 16 output fibres and 16 splices, each splice joining respective input and output fibres. In determining the quality of the splices, it is necessary to measure the light passing along the associated input and output fibres, and this is often difficult to do, particularly where access to a splice tray is hampered, as is the case where splice trays are mounted in racks. Thus, in order to make measurements on one of these fibres, using a conventional power meter, it is necessary to remove that fibre from the tray, which inevitably means disturbing all the fibres, with the attendant possibility of compromising the integrity of the signals carried by these fibres.
This situation can be improved by using a splice tray having only two spliced fibres. This considerably reduces the possibility of disturbing the signals carried by fibres other than that being measured. Unfortunately, the fibre being measured must still be removed from its normal position in the tray, which means that there is still a high risk of imposing unacceptably high bending losses on the fibre being measured. Consequently, measurement cannot be carried out whilst the fibre is carrying signals (that is to say whilst the system is "live").